Validated stability-indicating spectrofluorimetric methods for the determination of ebastine in pharmaceutical preparations

Analysis of clozapine in its tablets using two novel spectrophotometric reactions targeting its tertiary amino group

Two simple spectrophotometric methodologies have been proposed and validated for the measurement of an atypical antipsychotic drug Clozapine (CLZ). Method A depends on interaction of CLZ with N-bromosuccinimide(NBS) resulting in formation of a yellowish orange colored product, measured at 320 nm. The linearity range was 5.0-70.0 μg/mL. Method B depends on condensation of the same drug with acetic acid mixed anhydride reagent producing a purple colored product, measured at 319 nm. The linearity range was 8.0-24.0 μg/mL. All parameters affecting the reaction condition (volume of both reagent, temperature, time and the different diluting solvents) were optimized. Both methods were successfully applied to assay CLZ in its pure form and tablets giving mean percentage recoveries of (98.87 ± 1.8 and 100 ± 1.7) for method A, and corresponding values of (98.6 ± 0.96 and 99.5 ± 1) for method B. Besides, the study of reactions stoichiometry was performed and the reaction mechanisms were proposed.

Spectrofluorimetric method for determination of bupropion in pharmaceutical dosage forms

OBJECTIVE

Bupropion is a noradrenaline and dopamine reuptake inhibitor which is used as an antidepressant drug. Few HPLC and spectrophotometric methods have been reported before for the determination of bupropion. Most of the previous methods reported for determination of bupropion in pharmaceutical dosage forms are somehow dangerous to health and environment because of using organic solvents.

METHOD

In the present method bupropion was determined in pharmaceutical dosage forms by spectrofluorimetry after ion-pair complex formation with eosin Y. The ion-pair complex formation was optimized for reagent amount, buffer pH and time.

RESULT

The developed method was linear over the range of 3-120μgmL^-1 with an acceptable precision (CV<1.5%) and accuracy (Error<1%).

CONCLUSION

The present method is applicable for determination of bupropion in pharmaceutical dosage forms for routine quality control analysis.

Degradation Kinetics, In Vitro Dissolution Studies, and Quantification of Praziquantel, Anchored in Emission Intensity by Spectrofluorimetry

OBJECTIVES

A simple, rapid, specific, and highly sensitive ecofriendly spectrofluorimetric method has been developed for the quantification of praziquantel.

MATERIALS AND METHODS

A linear relationship was found between fluorescence intensity and praziquantel concentration in the range of 1-20 μg/mL in water at emission wavelength of 286 nm after excitation wavelength at 263 nm with a good correlation coefficient (0.999).

RESULTS

The proposed method was validated according to International Conference on Harmonization guidelines and statistical analysis of the results revealed high accuracy and good precision with the percentage relative standard deviation values less than 2. The detection and quantification limits were 0.27 and 0.81 μg/mL, respectively. The proposed method was extended to investigate the stability of the drug and its degradation kinetics in the presence of acidic, alkaline, and oxidative conditions.

CONCLUSION

The method was utilized for in vitro dissolution studies of praziquantel tablet formulation. The suggested procedures could be used for the assessment of praziquantel in drug substance and drug products as well as in the presence of its degradation products.

A fluorescent sensor for detecting dopamine and tyrosinase activity by dual-emission carbon dots and gold nanoparticles

In this work, we report a fluorescence strategy for detecting dopamine (DA) and sensing tyrosinase (TYR) activity on the basis of the dual-emission carbon dots (DECDs), which contain two emitters: the blue emitters (BE, maximum emission at 385nm) and yellow emitters (YE, maximum emission at 530nm). Gold nanoparticles (AuNPs) can effectively quench the two emissions of DECDs. The addition of DA aggregates AuNPs effectively, leading to the fluorescence recovery of dual emitters gradually. This strategy exhibits a high selectivity toward DA and shows good linear ranges, such as 0.5-3μM for BE and 0.1-3μM for YE. Additionally, the proposed method is successfully applied to the determination of DA in real samples with satisfactory recoveries. Subsequently, this DECDs-AuNPs platform is further taken advantage to assess TYR activity by the aid of TYR's capability for oxidation of DA into dopaquinone, which will not induce the agglomeration of AuNPs, so the fluorescence quenching of DECDs is associated with TYR activity. Finally, the mechanism of the reaction is discussed in detail, and the results suggest that both amine and phenolic hydroxyl groups of DA bring the aggregation of AuNPs.

Simultaneous Liquid Chromatographic Determination of Ebastine with Two Sympathomimetic Drugs Using a Monolithic Column

Ebastine (EBS) has been assayed in its laboratory-prepared co-formulated tablets with either pseudoephedrine hydrochloride (PSU) or phenylephrine hydrochloride (PHR) using isocratic reversed-phase chromatography. Separation was conducted using a 50 mm × 4.6 mm i.d., Chromolith® SpeedROD RP-18 end-capped column at ambient temperature. A mobile phase composed of water:acetonitrile in a ratio of 25:75 having a pH of 3.2, has been utilized at 1 mL/min with UV detection at 254 nm for both EBS and PSU and 274 nm for PHR which in turn increased the sensitivity of the proposed method significantly. Symmetric well-separated peaks resulted in a short chromatographic run; <5 min. The proposed method was subjected to detailed validation procedures and proved to be highly sensitive as shown from limit of quantification values which were 4.7, 39.4 and 10.2 μg/mL for EBS, PSU and PHR, respectively. The proposed method was used to analyze EBS in its laboratory-prepared co-formulated tablets; the obtained results were comparable to those resulting from the reference method.

Estimation Based on Emission Wavelength of Dabigatran Etexilate Mesylate in Bulk and Capsule Dosage Form

A simple, rapid, specific and highly sensitive spectrofluorimetric method has been developed for the quantification of dabigatran etexilate mesylate in bulk and capsule dosage form. A linear relationship was found between fluorescence intensity and concentration in the range of 0.01-1.0 μg/ml in dimethyl sulphoxide as solvent at an emission wavelength of 391 nm after excitation at 334 nm, with a good correlation coefficient (0.989). The detection and quantification limits were found to be 0.005 and 0.015 μg/ml, respectively. The proposed method was applied for dabigatran etexilate mesylate capsules, results reveal with percentage recovery of 102% and percentage relative standard deviation values were found to be less than 2 for accuracy and precision studies. The proposed method was validated for linearity, range, accuracy, precision, limit of detection and quantification according to International Conference on Harmonization guidelines. Statistical analysis of the results revealed high accuracy and good precision. The suggested procedures could be used for the determination of dabigatran etexilate mesylate in bulk and capsule dosage form in quality control laboratories of industries as well as in academic institutions.

Determination of galantamine hydrobromide in bulk drug and pharmaceutical dosage form by spectrofluorimetry

AIM

To develop a simple, accurate, sensitive, rapid and precise method for the determination of galantamine hydrobromide in bulk drug and pharmaceutical dosage form.

MATERIAL AND METHODS

The method employs wavelength detection and determination of galantamine hydrobromide at excitation wavelength 282 nm and emission wavelength 607 nm in a solution of simple distilled water.

RESULT AND CONCLUSION

The method was found to be linear in the range of 2-14 μg/ml having r (2) = 0.9999. The mean accuracy was found to be 98.12% to 99.67%. The intraday and interday precision was found to be 0.18-0.35% and 0.13-0.46%, respectively. The limit of detection was found to be 0.29 μg/ml. The limit of quantification was found to be 0.89 μg/ml. The method was successfully applied for the determination of galantamine hydrobromide in bulk drug as well as pharmaceutical dosage form.

Fluorimetric quantification of brimonidine tartrate in eye drops

A simple and sensitive spectrofluorimetric method has been developed for the estimation of brimonidine tartrate in pure and eye drops. Linearity was obeyed in the range of 0.2-3.0 ΅g/ml in dimethyl formamide as solvent at an emission wavelength (λem) of 530 nm after excitation wavelength (λex) of 389 nm with good correlation coefficient of 0.998. The limit of detection and limit of quantification for this method were 22.0 and 72.0 ng/ml, respectively. The developed method was statistically validated as per International Conference on Harmonisation guidelines. The percentage relative standard deviation values were found to be less than 2 for accuracy and precision studies. The results obtained were in good agreement with the labelled amounts of the marketed formulations. The proposed method was effectively applied to routine quality control analysis of brimonidine tartrate in their eye drops.

Validated stability indicating liquid chromatographic determination of ebastine in pharmaceuticals after pre column derivatization: Application to tablets and content uniformity testing

An accurate, simple, sensitive and selective reversed phase liquid chromatographic method has been developed for the determination of ebastine in its pharmaceutical preparations. The proposed method depends on the complexation ability of the studied drug with Zn²⁺ ions. Reversed phase chromatography was conducted using an ODS C18 (150 × 4.6 mm id) stainless steel column at ambient temperature with UV-detection at 260 nm. A mobile phase containing 0.025%w/v Zn²⁺ in a mixture of (acetonitril/methanol; 1/4) and Britton Robinson buffer (65:35, v/v) adjusted to pH 4.2, has been used for the determination of ebastine at a flow rate of 1 ml/min. The calibration curve was rectilinear over the concentration range of 0.3 - 6.0 μg/ml with a detection limit (LOD) of 0.13 μg/ml, and quantification limit (LOQ) of 0.26 μg/ml. The proposed method was successfully applied for the analysis of ebastine in its dosage forms, the obtained results were favorably compared with those obtained by a comparison method. Furthermore, content uniformity testing of the studied pharmaceutical formulations was also conducted. The composition of the complex as well as its stability constant was also investigated. Moreover, the proposed method was found to be a stability indicating one and was utilized to investigate the kinetics of alkaline and ultraviolet induced degradation of the drug. The first-order rate constant and half life of the degradation products were calculated.